Switching selector repeater



May 8, 1956 P. BAKKER SWITCHING SELECTOR REPEATER Filed Jan. 6, 1955 5Sheets-Sheet l ATTY.

May 8 1956 P. BAKKER 2,744,962

SWITCHING SELECTOR REPEATER SELECTOR REPEATER SWITCH 299 36.1

INVENTOR.

PIER BA KKER BY @W/wd ATTY.

rOI

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INVENTOR. PIER BAKKER ATTY.

United States Patent icc SWITCHING SELECTOR REPEATERv M Pier Bakker,Chicago, lll., assiguor to Automatic Electric Laboratories, Inc.,Chicago, Ill., a corporation of Dela.

Ware

Application January 6, 195s, serial No. 480,191)` 11 claims. (ci.179-18) The present invention relates in general to automatic telephonesystems and more particularly to switching selector repeaters for usetherein.

With the growth of automatic switching systems in the communicationslield, the eventual necessity of universal numbering schemes especiallyfor heavily populated. areas was early recognized and various'atternptsweremade for solving the problems to make such schemes economicallyfeasible. Each area had its ownp'articular problems; and solutions,which were advantageous for one area, were not always suitable for otherareas. 4'

In many areas'there grew, due to various growth patterns and economicproblems, telephone systems vhaving several interconnected main oilceseach ofwhich had smaller exchanges subsidiary to them. it was oftenfound advantageous, if not imperative, to assign one or more.

of the initial digits of subscriber numbers `at a main oce for initialdigits in subscriber numbers at its regy spective suboflice or suboices.It soon became apparent. that such systems would require universalnurnberingrzifl a good grade of service were to be provided ata reasonvable cost to the customer. It is with this type of a system. ,1

that the present invention is concerned.

Very early in the art, it was found advantageous to install specialequipment'in the first switching stage of the suboice, such equipmentproviding for the simultaneous transmission of certain initially dialeddigits to the main exchange and absorption of said digits by the firstswitching stage at the suboice. In response to subsequent digitsreceived, said special equipment, commonly'referred to.

Patent No. 1,542,958 issued June 23, 1925, to Ray. Thisy disclosureshows the use of an extra control wiper and' marked bank contactsaccessible thereto for providing for' the absorption of initial digits.This method has lthe important advantage of reduced wear on theswitching selector repeater; for example, the switch does not drop backon the first digit when'it has not yet been determined whether the callislocal or to the main office.

It is an object of the invention proposed herein to provide anarrangement somewhat similar to that shown in said patent but havinggreater simplicity and exibility. The applicant has utilized normal postsprings together with new circuits in combination with marked extracontrol banks for achieving the necessary control functions ,in theselector repeater. The marked extra controlt banks are critical inresponse to second digits while the normal post springs are critical inresponse to rst and third digits.

Several advantages are gained by the i combination of I utilized in thepresent invention:

2,744,962 Patented May 8, 195.6

normall post springs and marked extra control banks as l. Provisionismade for switching through connections in response to arst digit-e. g. 0to reach the operator. p

2. A' more eicient use of numbers available formain office directorynumbers is obtained-e g. all numerals l-0 are available as second digits.of main oflice directory numbers. v

`3.` The need for special wiring of thekextra control banks iseliminated forv all circumstances.

4. Provision is made for switching through connections in response to afourth digit after the third digit has determined that the call is localandhas caused the wipers,

to return to normal.

A feature is the `economy which is gainedbecause vall the extra controlbanks of the switching selector repeaters in a shelf can be multipled.Because the switching .selector repeaters will properly complete theirfunctions Y.(as described in more detail later) even though .three orfour of them simultaneously test for resistance ground potential on theextra control banks, itwill'bedpossible in small exchanges-having, forexample, only ten such switches in a shelf-to multiple all extra controlcontacts in each switch, to which the same potential isto beconnected,,i,n

addition to multipling the extra k'control,banks of alli/(hel. switches.

Another feature is n y three digits have determined that ,a localsubscriber isbeing called for switching through connectionsinfrelsponseA tofthe last of said three :digits or in response toa'fourth digit, dependent upon which of two optional; wiring schemes isused. y Y The applicant-achieves another advantage combination of normalpost springs and extra controlcontacts. In the above-mentioned patent toRay,I` themarkingf of the extra control contacts is used to determinewhether repeater must be operated at least once to move the Wipers. tothe rst bank contacts. Thena test` must bemade over,V the yextracontrolwiper to yprevent further rotary`move-...

ment of the wipers if the marking on the. extraV control contactindicates that the ,call is to the main office. using normal postsprings for this purpose, no s uch test is necessary; and no rotarymovement ofthe wipers is necessary if the call 'is to the main otice. y.d Other features will be evident upon a perusal of the followingdescription in which:

Fig. l shows in block diagrarnthe arrangement of.

Figs. 2 andf3 show the selectorrepeater infdetail: v f. Fig. 4 shows thewiring of the extra control bank contacts of the selector repeater; and,

Fig. 5 shows a secondary lineswitch individual yto Vthe selectorrepeater and shows, in block diagram, a main` oliice and a trunkextending from said lineswitch to said main oice. y d

The preferred embodiment shows a two-motion vertical and rotary step bystep selector repeater switch and a single motion rotary lineswitchconnected thereto. .When a calling subscriber in a subofiice isconnected to the selector repeater, he is also connected to switchingequipment in the main oice by way of the lineswitch.

The first digit dialed by the subscriber is repeated to selectivelyoperate the switching equipment at the main office; and said digitcauses the wipers ofthe selector repeater to be raised to a desiredvertical level. If the left normal post springsl operate in said desiredlevel, thev selector repeater will search for and seize an idleY outletin said desired level and connections to the main oice `themeanselfective, after Y rst will Vbe released. However, if .said leftnormal post springs *f dornotw operate' 'inrsaid desired` level',l thewipers' are held in said vertical position until a second digitcausesvthe wipers to be rotated to a desired rotary position insaiddesired level. Said second digit is also repeated to the main oce toselectively operate.switchingiequipinent therein* v If' the extracontrol wiper finds resistance ground potential connected to the contactit engages in said desired rotaryposition, the wipers of' theselectorrfr'e'p'eatei" are renderedtineiective and the' call iscompleted byzway of the mainoiice in a normal manner.

' If'lthe eXtra control wiper lnds direct'ground potential connected tothe contact it engagesin said desiredrotary position, the wipers'of theselector yrepeaterare restored.

thevse'llector'repeatertofbe raised'to a desiredlevel, If` the right`normalp'ost springs do notop'erate inthislatter' desired level, thewipers of theselector 'repeaterarercnderedbinetfective; land thefcallis' completed by'way'of the rnain'oiiice inthe norrnalmanner. However,ife'fthe rightnormal post springs do operate insaidlatter d'efsired1eveljthey operate means whereby thejcall "is" c'establishczd"4l'callyineither of'two' waysdepending"upbnlwhichfoff twohwiring schemesis used and whereby connect'insto" the' main "oilicej arei released. VIfone of"`saidwiring schemesl is" used,1 the' wipers ofthe `selector"repeater "will befrotat'ed over saidlatterv desired level to searchforand siz'e'f'anidle outlet in the normal manner. i If the otherwi'rin'gscheme is used, the right normal postlsprin'gs will' operatemeans for causing the wipers to bere'stored-to n'orm'ala second time;then, in response to a fourth digit, thefwpers willbe raised to adesired vlevel then rotated into said l'evel vtoV search for andseize'an idley outlety in' the riorr'nalv manner.

Seizure of switching selector repeater 299 Assume' that the subscriberat substation 290 desires toj'callt'khe' local operator and that thevoperator "can, be reached 'over the '0' level of selector repeaterswitch 299.' Whenfthel'handsetis'removed from the cradle"atVsbstation290, the subsciiber'willbeconnected to switch`299 amanner`well known in the art by way of the line conductirsV 2194A and 295, linecircuit" 291, and the 'finder 2'92-funder control of allotter 293. Theline'relay R220' Will be 1operated 'overa circuit comprising`v batterythroilgh the lower winding ofR2'20, contacts 216 and 201, conductor"211,finder 292-,"line circuit 291, conductor 294, Vsubstation290, conductor295, line circuit 291,"iinder"292, conductor 212, contacts-203` and 218throughthe upper winding of R220 to ground. At contacts 221, R220conrplete's connectionsto the secondary lineswitch l500;l atcontacts"'222,` R220 'completes an obvious circuit for operating thehold relay R246, At contacts" 242, R240 completes an obviousk circuitfor' operating` relayz'R2`2'5; at contacts 243, grounds the 'privateconductor 213;"at

contacts '244, completes 'obvious circuitsfon operating the changeoverrelay R260 and for energizing` the left windingofthe shunt field relayR215, but R215 doesjnot operate except when both windings are energizedlin thez way of contacts 26'1 and 228'resprectively. Relays R225 and'R230lfunctio'n in a manner well'krrownunthe'art tovr release *outgoingconnectionsto theY maino'f'icel ifthe" subscriber delays too long beforedialing or if a fault `occurson'the4 line 'so'fhata conductiugpathispermanently established across conductors 294 and 295. Bricy, groundpotential is momentarily established on conductor 297 periodically bytiming equipment (not shown) and R230 will be operated. At contacts 235and 234, R230 respectively opens the original operating circuit of R225and connectsR225 to conductor 298 by way/of--contacts 227, 242'and'234.At 'this moment, ground potential is connected to conductor 298 sothatfR225'remainsa operated. After a predetermined timewinterval,abe-timing equipment will remove ground potential from conductor 298;and R225 will restoreto-open connectionsr to the secondary lineswitch500 at contacts 226 and,'due to R230 lighting an alarm llamp 267 atcontactsl232, the fault will be found and corrected; however, if thesubscriber dials the rst digit and if the changeover relay R260 restoressubsequent to the termination of said rst digit in` a manner to bedescribed below, all before R225 restores,

then relay R230 will berestored'at contacts 261' and the originaloperating circuit of R225 will be recompleted.`

When'R260 operates as described above, it' prepares at contacts 262 alocking circuit for itself; "at Vcontacts 263,`

M further prepares the above-mentioned circuit for operating'thevertical magnet M280; and, at contacts 265, prepares a circuit for thestepping relay R310'.

LWhen;l as describedv above, the line relay R220 operated ,1,contacts221`to` extend connections to the secondary line'- switchj500,the yline relay R520 of the lineswitch operated overa'circuit extendingfrom ground through the 'winding of'R5120, contacts 514, kconductor 364,contacts 231, 221 and" 284, I'through the right hand winding of theshunt `field relayR215, conductor 361, contacts 301, conductorswitch-1500 visidle.

` 542', contacts 5,11, lthe upper'non-inductive winding of the switchingrclay R510 through the normally operated contacts 9551of the all'ytrunks busy relay'R550 and through resistance 545 to battery. Theshuntiield relay R215 willn not operate because its two windings areenergized withtheirtrnagnetic vields aiding, and` R510 will not operateover itsiuppern'on-inductive winding.

As iswell known inthe art, the all trunks` busy relay R550will remainoperated as longas'one of' the trunks extendingto the main vofiice 573and accessible to 'line- A At contacts 522, 523 and 524, R520extends`"'partial connections to wipers 546, 547 and 548.'

Atcontacts: 524" and 525, R520 connects the rotary magnetMSSO to "theprivate wiper. 548 by way of contacts 531,A 52`5,'516"and` 524. If thetrunk upon which the lineswitch'Slltl'is standing is idle, batterypotential will beconnected to its private contact; but, ifA the tmnk isbusy,"ground potential will be connected to. the private contact-4e. g.when trunk circuit 570is seized by a lineswitch -other than lineswitch500, said other lineswitch and its selector'repeater extend ground to'the. private bank contact ,to which relay R580 is connected to operateR580 and'to niark" trunk circuit 570 busy. Therefore,v if theprivte'wiper 545 engages the private contact of a busy trunk,' groundpotential will be extendedback over wiper 548 and contacts 524, 515,V525 and 4531 to the winding of'tlie'magnet `M530 to energize saidmagnet. At contact`s 531', lM530 will open its operating circuit andrestore.y

Uponk the restoration of magnet' M530 the wipers 546,

' 547and'5i48will be'advancedto the contacts of the next lcontacts 319,conductor 3,77 and ground potential on contacts229. 4The magnet M530does not operatein this 7 circuit due to the high resistance Winding ofR510. They idle' trunk circuit relay, corresponding to R580 will beoperated by R510 over a circuit extending from ground, overcontacts 229,conductor 377, contacts 319, conductor 544, contacts 517 and 524, wiper548 and a conductor corresponding to conductor 562 to said trunk circuitrelay. When R510 operates over its lower winding as described above, itcloses contacts 512, 513 and 517 to extend connections from theswitching selector repeater 299 to the idle outgoing trunk by way ofcontacts 522, 523 and 524 and wipers 546, 547 and 548. At contacts 515,R520 locks itself-operated in series' with M530 over kan obviouscircuit. In a manner well known in the art, `an incoming first selectorin the main otice 573 is seized.

The seized first selector in the main oce will return Idial tone in amanner well known in the art to the calling subscriber by way of thenegative conductor 560, wiper 546, contacts 522 and 512, conductor 542,contacts 301, conductor 361, capacitor 224, contacts 201, conductor 211,tinder 292, line circuit 291, conductor 294, substation 290, conductor295, line circuit 291, nder 292, conductor 212, contacts 203 and 218, toground on the upper winding of R220.

The switching selector repeater 299 and the seizediIst selector in themain oce 573 are now ready to receive a first series of impulses fromthe calling substation 290.

It will be noted that R510 is a slow to operate relay; and, therefore,it cannot operate to switch through connections before the line relayR520 operates. It is necessary that R520 operate tirst to test for theidle or busy condition of the trunk to which the Wipers are connected.

It may be well to mention that busy tone will not be returned at thistime to the calling subscriber at station 290 in case that alltrunks tothe main oice are busy' because it has not yet been determined whetherthe call is local or to the main oice. If all trunks are busy, relayR550 will have been restored to open contacts 551, thereby to preventthe operation of the line relay R520 when the secondary switch 500 isseized as de scribed above. However, relay R510 will operate over thecircuit described above. Certain second and certain third digitsdetermine that a call is to the main oice. AS will be described below,the contacts of relays R220, R225, R240, R250, R335, R345 and R510 willbe in their operated positions at the end of a second digit which hasdetermined thatl the call is to the main olice; and said relays willextend busy tone from equipment (not shown) to the calling subscriber atthe end of said .second digit by way of conductor 248, contacts 241,conductor 368, contacts 337, conductor 367, contacts 1252, conductor366, contacts 346, conductor 541, contacts :521and512, conductor 542,contacts 301, conductor 361, capacitor 224, contacts 201, conductor 211,nder 292, lline circuit .291, conductor 294, station 290, conductor1295, line circuit 291, finder 292, conductor 212, contacts 4203 and`218through the upper winding of R220 to ground. As will be described below,the contacts of lrelays R220, R225, R240, R250, R335 and R510 will be intheir operated positions, the vertical olf normal contacts 313 will beoperated and the vnormal post springs 314 unoperated at the end of athird digit which determines that the call is to the main oice; and busytone will be extended to the calling subscriber at the end ot said thirddigit by way of conductor 248, contacts 241, 'conductor 368, contacts337, conductor 367, contacts ,352, conductor 366, contacts 314, 326 and313 and thence to the calling subscriber over a path similar to thatdescribed above for a second digit which determines that a call is tothe main oice.

1- It is apparent that, if all trunks to the main otice are busy whenselector repeater 299 and lineswitch 500 are seized, -dial tone must bereturned to the calling sub- .scriber locally rather than being returnedfrom the main 6 office as described above. equipment (not shown) overconductor 249, contacts 251, conductor 366, contacts 336, conductor 541and thence to the calling subscriber over the busy tone path describedabove for a second digit which determines that a call is to the mainoice.

It will now be assumed that the calling subscriber at station 290 hasbeen connected to the selector repeater 299 and to the main ofiice 573by Way of lineswitch 500 and trunk circuit 570 in the manner describedabove. Relays R220, R225, R240 and R260 in the selector repeater 299 andrelays R510 and R520 in the lineswitchl 500 are operated.` Dial tone hasbeen extended to station 290, and the calling subscriber dials the firstdigit.

Establishing local connections in response to a first digitleft normalpost springs operate Assume that the subscriber dials 0 to get theoperator. The line relayl R220 restores then energizes in response toeach impulse. Slow release relay R300 is operated by the rst restorationof R220 over a circuit comprising contacts 210, 223 and 247 andconductor 382; and, being slow to release, R300 is maintained operateduntil the end of the digit. The vertical magnet M280 is operated inresponse to each restoration of R220 over a circuit comprising contacts210, 223, 247 and 263, said magnet raising the wipers 390-393 to aposition opposite to the contacts in the tenth level of the bank, inwhich position the left normal post springs operate to close contacts394 and 395. When the wipers are raised vertically, the vertical offnormal springs 281 close to operate the slave relay R250. At contacts251, R250 opens the operating circuit of the changeover relay R260;however, R260 ismaintained operated over a locking circuit includingcontacts 262, conductor 378, contacts 305, conductor 377 and contacts229 until R300 restores at the end of the digit to open contacts 305.

At contacts 221, relay R220 repeats the impulses tothe main olce 573 byway of line switch 500; at contacts 302, relay R300 short circuits theright handwinding of relay R215 to improve pulsing to the main otice.The impulses repeated to the main otTice selectively operate switchingequipment (not shown) therein in a manner well known in the art toextend various connections. v

When the slow release relay R300 restores at the end of the tirst digit,it opens contacts 305 in the locking circuit of the changeover relayR260 and closes contacts 304 to partially operate relay R315 over acircuit extending from ground over contacts 229, conductor 377, contacts304, 321, 347 and 340, contacts 394 of the operated left normal postsprings, conductor 375, the upper winding of R260, conductor 376, thelower winding of R315, contacts 320, conductor 380 and through thewinding of the release magnet M286 to battery. This latterv circuit alsodelays the restoration of R260.

Contacts 318, which operate when R315 is energized over its lowerwinding, cause R315 to fully operate and lock itself operated over acircuit including its upper winding, contacts 31,8, conductor 374 andcontacts 243; at contacts 317, R315 connects the switching relay R200 tothe private wiper 393 by way of conductor 373, contacts 317, conductor372, contacts 205 and conductor 371; at contacts 319, opens the circuitof the private conductor`544 to restore relays R510 and R580 thereby torelease the line switch 500 and to release the seized switchingequipment in the main olice in a manner well known in the art; atcontacts 320 and 321 opens its original operating circuit which hasmaintained slow release relay R260 operated; and, at contacts 323,operates the stepping relay R310 over a circuit extending from battery,through R310, contacts 323 and 330, conductor 387, contacts 257 and 282,contacts 265 of the slow release relay R260 which has not yet restoredand ground on contacts 281. At contacts 311, R310 oper- The tone isextended fromy atesnthe 'rotaryA magnet; M360 over: a icircnitextendingfromi :ground :on contacts 229, overl f conductor 377;. and 1 contacts304-and 311 tozbattery-on the windingvof M360.;y and,.at contacts, 312,extendsfground from contacts 210,V

over-conductor 333',` contacts 312 andy conductor the switching relayR200 to short-circuit-R200 thereby to'prevent its operation. `M360 stepsthe wipers S90-..393 tothe first-contacts inthe level. When,.the.changeover relay R260- completely restores, it restores R310 at contacts 365;and, at contacts 311 and 312-respectively, R3-10..restores` theA magnetM360 and removes the short circuit from, the switching relay R200. Atcontacts 26.6 and.: 361, R260. and r M360 `connect vthe steppingy relayR310 to the private wiper 393 in parallel with the switching relay R200over a circuit extending fromthe wind# ing?of--R310,f contacts 323 and330, conductor' 387,` contacts 257, 2821,-.and 266, conductor 385,contacts 361, contacts 317, conductor 372, contacts 205 and conductor'371 towiper-393`.

Connections -to` thesmain oce have beenv released and theselectorrepeater 299 is nowV ready to Search forand seize-1an idle lineto the operator-position (notshown) in-the 0 level'.v Selector repeater299searchesfor absence of'fground in a mannerwell known inthe art,ground potential being connected only to the-private--contacts--KVaccessibletto private wiper 393-of-=lines that are busy.

If wiper 393 encounters groundl potentialon the-privatecontact of therst'line intheO level, indicating-that said li'neis busy, the steppingrelayR310 isoperated by way of wiper? 393 over the above-mentionedcircuit to;

re-operate the `rotary magnet-'M360 -over` its above-mentioned circuit.M360 stepsthe Wipers 390;-393to the contacts'of theV next accessibleline andv restores R310 at contacts-361. R310 opens contactsf311 torestoreM360.

This cycle taf-operation is repeated-vuntil'an idle lineisfounderuntilthe wipers 390-393 are stepped-Ato the eleventh rotary position, inwhich position busy tone is returned to the calling subscriberbywayoffconductor 248, contacts 241, eleventh rotary earn springcontacts 235 and thence to the calling station 290by=way of call-- ing'line conductors 294'V and 295,'linecircuit 291 and nder 292 in amannerwell known in the art.

i Assumingthat the wiper `393 flndsfanidle line, the switching relayR200 operates-1in series with the-stepping relay R310 over acircuitrextending fromground, over contacts 243, R200, conductor 373,contacts 361, conductor 385,` contacts-'266; 282 and'f257,y conductor387,v and cont-acts `330afnd 323'-tobattery onf'thewinding ol-R3`10.`The stepping relay R310- does not operate in this circuit due to thehigh resistance winding of the switching relay R200.

v-At contacts 202and 204, relay R200 extends connections from vthecall-ing line to the line wipers 390 and 391'; at'contacts- 206,completes a path for returningthe holding ground potential from theoperator-'position in a mannerl well'known in the art for holding R200and R315 operated; at contacts'202 and 203,l restoresvthe-linerelayR220; and, at contacts 209, restores the hold relayR240iand opens a point inthe operating circuit of the release magnetM286. At contacts 242, R240 restores relay R225. Atfcontacts 221, relayR220restores relay R520.

-Connections are 'now established to -theoperatorposi tion', and anyfurther connections will be established in a manner well known intheart.

When 'the calling subscriber abandons or yterminates the call, hewill-replace the handset'to open 'the calling line circuitwhich, in amannervwell known in the art, controls equipment seized by way of wipers390, 391 and 393 to remove'the holding ground potential 'from theprivate contact accessible to wiper 393. Removal of ground potentialfrom said contact will cause the line circuit 291 and finder 292torestore to normal andwill also restore relaysR200and R315.lR200.operates the'release magnet M286 over: a circuit extendingfrom-ground, overcontacts restored, condition ancLcan be seized.forlcompleting, another calL,

.It will .bennderstoodthan althoughther-preferred em bodiment lshowsonlyone level utilized for singledigit lswitching as described aboveother levelscan be` similarly arranged.

UsefofA-switch 2.99as arepeater determined bythe second digit-wipe 392 1engages a bank contact havingf resist#4 ancevv ground'connected theretovAssumenowthat the subscriberat station 2,90 dial/s a firsty digit 3after his station has; been connectedto the selector repeater'299 and.to the main oflce 573 all in va, manner previously described, As,`described above, relays R220', R225',` R240 and' R260in the, selectorIrepeater 299u andrelays' R510 and. R520l in `the line switch 500.wi11..have been operated incident to the seizureof theselectnor repeater 299.

In a manner described above, the impulses will be repeated to themainexchange 573 to selectively operate switching equipment therein;`R300'will operate; and the vertical-'magnet M280 will raise thewipers`390-'393 `to aposition 'before the third level in the contactbank. The slave'relay R2501operates as described abover when thewipers-"are-raised-off thevertical normal position.' lRelays R260'andR300 restore at the end-ofthe digitbut, becauseV the^-leftnormal'postspringcontacts 394 ldo vnot operate, relayd R315cannot'loperate, nor can the 4stepping-relay- R3-10operate.-f The-rotarystepping of the wipers is thereby :preventedv However, a-circui-t-,foroperating therotaryI n`y1agnetfM360`v in response to a second digitisprepared.

lWhen the seconddigit; for example 7, is received,

relays R220gR225, R240 and R250of the selector repeater- 299taswel1-asrelays -R510and R520 are in their operated positions.A The rstirnp'ulseofsaidsecond digit restoresV then reoperates the -line'relay R220- Atcontacts R223, R220 operates relay lR300 over a circuit-extending fromgroundover contact's'310, 223 and 247- and conductor-382 to batteryonR300: and #also operates the rotaryA magnet M360 `over a -cireuitlextending frorngroundI over contacts 210,*2233-247 and 264,-conduetor-381'and contacts v344 and "322' -to battery on 'M360 Slowlrelease relay- R300y will --be heldloperated`v dur-ing the succeedingsiximpulses and'` M360 -will-be operated in response to eachimpulseto.move the'wipers 390-393 to-the seventh rotary'position in'- the`thirdflevel of the scontact bank. At 'contacts 303, R300-hasopened-thc-circuit-for the marginal relay `R355- so'that the potentialmarkings on the extra controlfcontacts are of noelect until R300restores a't the end' ofthe secondI digit, at which time the-wipersv390-393 :have ybeenstepqned r to the-desired position=in the contactbank, in thiscase the seventh rotary position inthe third level.

"When R300 restores at the end of said second digit; it. closes-contacts `303 to connect he marginalI 'relay R355tot.

Z by way' of contacts 338, 316andf'2303l and wiper392..l Relay 'R355operates-,only contacts '359 when .sonconnectedto resistance' ground.RelayR345tis.partiallyy energized over an obvious.- circuit. includingcontacts: 359,-" whereby onlyf zcontacts.- 350.a1'ey operated; R345 thenoperates fully over a circuit extending' from battery, over.the-lower'winding of R345,.cxmtactsv 350, conductor 386 .and contacts,`281. At-contactsrs347, R345wprevents the-operation of relay ,R315inftheevent. that the,rghtnormalipostA spring.,contactsz399zare Openated andrconductors396= and 397A areiconnected whenrelay R335 operates,and at contacts ,348, R345P,21 rtiallyA operates relay :R335: over. a`circuit extending frQlnigfQllLld, over contacts 2.29y .l conductor3177,r contactszt.. 3.21 and; 348, the lower winding. oflR335,contacts). 343.,..and:-Qn duetor 380.through the. windingorme releaseVmagnet.

M286 to battery. M286 does not operate in series with VR335 nor inseries with the resistance 388 to which M286 is also connected by way ofconductor 380, contacts 320, conductor 379, contacts 254, conductor 384and contacts 349 and 358. Relay R335, when energized over its lowerwinding, operates only contacts 342 which contacts operate R335 fullyover a circuit extending from ground, over contacts 229, conductor 377and contacts 342 to battery on the upper winding of R335. At contacts338, R335 restores relay R355; at contacts 343, opens its originaloperating circuit; and, at contacts 344, prevents the operation of therotary magnet M360 in response to succeeding digits dialed by thecalling subscriber.

The second digit 7 is also repeated to the main exchange 573 toselectively operate switching equipment therein in a'manner describedabove. The selector repeater 299 is now in a condition whereby localswitching cannot be elected, and also it is ready to receive ra thirdseries of impulses. The third and all subsequent series of impulses willcause connections to be made by way of the main oce 573 in a manner wellknown in the art. When the call is answered, battery connections on theline conductors will be reversed in a manner well known in the art. Thiswill cause the windings of the shunt field relay R215 to be energized sothat their iields oppose to operate the contactsof R215 for purposeswell known in the art, e. g. metering.

It ywill be notedthat the extra control contacts in all levels exceptthe O level have been Wired. However, if all of the subscribers that canbe reached by the subscribers in the subofce and by way of the mainoiice have directory numbers with the same first digit, 3, then it isapparent that only the third level of the selector repeater 299 need bewired. The marginal relay R355 may be one of many relays well known inthe art which will properly function to close only contacts 359 over aconsiderable variation in power supplied thereto. It is not unusualthat, if three such relays were simultaneously connected to theresistance potential normally used to operate only one relay, they willstill operate properly. This permits multipling the banks of theselector repeaters.

Use as a repeater determined by the third digit-wiper 392 encountersground to restore switch after second digit. Right normal post springsdo not operate when third digit is received Assume that the callingsubscriber at station 290 has been connected to the main otiice 573 andto the selector repeater 299, that the wipers of the selector repeaterhave been raised to the third level in response to a first digit 3 andthat the subscriber now dials a second digit 6, relays R510, R520, R220,R225, R240 and R250 being in their operated positions, all in a mannerdescribed above.

In response to said second digit 6, relay R300 and the rotary magnetM360 are operated over circuits described above, M360 stepping thewipers 390-393 to the sixth rotary position ofthe third level, in whichposition wiper 392 encounters ground potential. When relay R300 restoresat the end of said second digit, it closes contacts 303 to fully operaterelay R355 over a circuit extending from ground on contact 401, wiper392 and contacts 303, 316 and 338 to battery on R355.

At contacts 356, R355 completes an obvious circuit for fully operatingrelay R345. At contacts 350, relay R345 locks itselt` loperated over apreviously described circuit; and, at contacts 349, extends groundpotential from contacts 356, over contacts 349, conductor 384, contacts254, conductor 379, contacts 320 and conductor 380 to the release magnetM286, thereby to operate M286 and to short circuit the lower winding ofrelay R335, whereby the operation of R335 over a circuit previouslydescribed is prevented.

The release magnet M286 operates to restore the wipers 390-393 tonormal, relays R250 and R355 restoring.

. scribed in the preceding section.

At` contacts 253, R250 reoperates the changeover relay i the releasemagnet to ground on contacts 229. Before" relay R345 restores, relayR335 is operated in series' with the release magnet M286 over a circuitpreviously described; M286 as described above will not operate over'this circuit, but is maintained operated over the circuit.

However, when R335 operates, it opens said circuit at contacts 343 torestore M286. R345 restores in response` to the restoration of M286.

The switching selector repeater 299 is now prepared for lthe receipt ofthe third digit, which digit we will assume to be 0. Relays R220, R225,R240, R260, R335,

R510 and R520 are operated at this time.

In response to said third digit 0, ten impulses are repeated to the mainoice 573 and the wipers 390-393 are stepped to the tenth level by thevertical magnet M280. In said tenth level, contacts 399 of the rightnormal post springs are not operated. With relay R335 operated, rightnormal post springs 399 not operated and the wipers of the switch in avertical ot normal position, that part of the switching selectorrepeater 299, which provides for switching through local connections,`isrendered ineffective; and all digits thereafter received by selectorrepeater 299 will be repeated to the main oce 573 in a manner describedabove to establish a connection by way of said main oilice.

It is apparent that connections may be completed by way of the mainoiice 573 in response to any third digit. except those which establishlocal connections.

Operation as a selector determined by the third digit-- i.

switch through in response t0 said third digit Assume that the callingsubscriber at station 290 has'` been connected to the main ofiice 573and to the selector repeater 299, that the subscriber has dialed thelirst twov digits 36, that said digits have been repeated to themainzoice 573 and that the selector repeater 299 has beem operated andrestored to normal all in a manner de- R240, R260 R345, R510 and R520are operated and the selector repeater 299 is prepared to receive thethird digit which we will assume to be 2. It will further be assumedthat conductor 397 is connected to conductor 396 and that conductor 398is not connected to conductor 396. v

In response to said third digit 2, the line relay R220 operates relayR300 and operates the vertical magnet M280 to cause the wipers 390-393to be stepped to the second vertical level all in a manner describedabove. The contacts 399 of the right normal post springs are operated bythe shaft of selector 299 when the wipers 390-393 are in the secondvertical level. As described above, the vertical 0E normal contacts 281and slave relay R250 are operated, and at the end of said third digitrelay R300 restores. At contacts 304, R300 partially operates relay R315over a circuit extending from battery on the release magnet M286 overconductor 380, contacts 320, the lower winding of R315, conductor 376,the upper winding of R260, conductors 375, 397 and 396, contacts 399 ofthe right normal post springs, contacts 341 of relay R335, contacts 347,321 and 304 and conductor 377 to ground at contacts 229. As describedabove, relay R315 operates fully, connects the switching relay R200'towiper 393, locks itself operated, releases connections to the mainoliice 573, opens its operating.' circuit to restore relay R260, andoperates the steppingv relay R310. Also as described above, the steppingrelay R310 operates the rotary magnet M360 once to step the wipers390-393 to the first rotary position in the second...

Relays R220, R225?,

levelgof ithe tcontact l 4b ankawhenr R260? restoresffter; a

shortrdelay, .thefsteppingfelay R310f3is` restored-.as wellVaszthenrotaryv magnet'` M360111andfthexfstepping relayfR310 t isconnectedl tothe privatewwiper R393" in parallel with selector:repeater: 299 will ina mannerdescribed yabove search for an idle'outlet in said secondlevel and switch through;connectionsathereto.

Itiswapparentnthat any one or'more, ofythe levels 1 9 of .the selector`repeatery 299v may be utilized .for extend-v 110.

ing-:local connections'in -responseto; certain ysubscriber numbershaving'rst and second-.digits 3- and 6 yrespectively.

Operatt'on' as a `selector determined fby third digit-"switch 1 throughin response tothe'fourth digity Assume thatl .the subscriber atstation290'has been connectedr.to;the1main exchange 573 and to the switchingVselector repeater 299,y thatsaid` subscriber has dialed the digits ,3,andy 6that saidxdigits havebeen repeated to the 20.

mainoice'573 to-selectively `operate switching equipment therein,.thatthe switch 299 has :been operatedin response torsaid two digits andrestored to normal all' in a mannerdescribed above. Assume further that.conductorv 398 is rconnectedto conductor 396 andthatconductor 397 is`25A not .connected toV conductor 396. Relays R220, R225,R240,=.R260,"R335, R510 and R520 are ,operated =at.this time,.,and aselector repeater '299 is now Aready to receive a thirddigit vwhich wewill; againfassumeto `be*` digit 2.

Inthemanner described in.the'precedingsection, the: 30

receiptof said `third digit 2 will; causetthe` wipersy to be stepped tothe second vertiealglevelvin'which level contacts-3:99am operated andrelays.R250 and VR300-will begoperated. At the Vend ofsaid "thirdffdigitrelaysf R260 and R300 are restored; andi at'contacts; 304, R300 willv.35.'

operate relay R325 over the circuit extending from ground overv=contaets 229, conductor 377, contacts 304, 321, 347 and 341, contacts399 of the right lnormal postsprings, conductors 396 andr398. andthrough thetupper winding operated` over acircuit includingconductor386gand .vertical ;otf.normal contacts 381; at `contactsf327,prepares acircuitV for-operating .relay R315; and, at. contactsf1328,A shortcircutsthe lower winding of R315V and operatesthe releasezmagnetM286'jby extendingthetground potentiaL 4 5v stores/,torremove the .shortcircuit from; the `lower wind-ings; 50,

of R315 to permit R315 to partially operate over ,a circuitextendingrom; ground overcontacts 229-, conductora377, contacts 327Ithelower winding .ofv,R3.15 contacts.A 320,-A conducto1-380:through lthe release, magnet' .M2-8.6` to' bat.

R260; thevertiCaloi-normal contacts*:.281nopentto: open' one.l holdingacircL-lit of relay.- R325," however1R325 i'sdleld, operated over acircuit including; itsfupper winding, .con'- taets 328l` conductor 38,4,contacts 287' oftathetY Jelease violislyx described.' "Whenzthe:'verticali olf :nor-mal`zspring. contacts 281 fclose, slave relay R250then @steppingx-relay r: R3.10:.:operater over circuitspreviouslyf'described. When r a switching relay R200 in a mannerdescribed above.y The: 5 ."atthersend `ofvsaidfourth zdigit, .relay R300restores;:theiholding circuit'foriR260 is `opened and'thezrotaryfmagnetf M360 is energized torotate the wipers"390-393t01he".rstfbank-.contactsiinthe second level andto restorethesteppingrelayR310.v Whenthe changeover relay R260 restores', .thefwipers` will be rotated to an -idley outletfin. a

manner ypreviously described under the control oflthe" stepping relay.R310, '.the switching .relay'R200 'an'd the` rotary magnet M360.

Attentonis: directedtto the fact thatthe wipers -will y be"'raised.thenxrotated in response yto any fourth 1digitA after a'thirdrdigitrestoration ofthe' selectorrepeater299 as described in tthis section.The ktenthlzlevcl is icon nectedv to theoperator position; and,therefore, thelnu-A meral 0 cannot be utilizedl `as the fourth digitlofalocal i number asidescribed in this section; Accordingly,lthe .ap-y vplicant. herein. has .provided means v fory forcing thelwipers 'L totheeleventh rotary position. to :give a` busy-signal in` casesthati a-localsubscriber accidentallyV dialssa fourth digit; 0. In such an event,the\wipers will be raised totheftenth Alevelpin which positiontheleft-normalpost springs operate lto close contacts-395y Thisextends"ground potential from contacts 243, over conductor-374;4

contacts 339, 395v and- 317, conductor 372, contacts"20`5 and conductor371 to the'private wiper 393, to' continu-- ouslyshort circuit.the'switch relay R200'andto'cyc1ically operate the lstepping relayR310.- and= the 'rotary-'magnet M360 untilthe wipers arel rotated to theieleventhrotary The cam springs then 'oper` positionlin the tenth level.atextorprevent lthe reoperation ofl the steppingrelay R310' vatfcontacts'2821and to-complete at contacts l284=a previouslyfdescribed 'circuitrfor extending busy tone'l'to -the calling subscriber.

While 'there has been described"- whatl sat present believedfto fbe the'preferred embodimentv of vthe invention,

it willbe understoodk thatfvarious lmodifications'may-bev made therein;and, it is contemplatedtocoverin the `'ap-v pended clairnsall suchmodiications as fall within. the` aocerandjnfzthe main'otiice, eachselectorfrepeater' having-.a ivipertsetrincluding a specialwiperrwitha`plurality oft primary andsecondary'positionspbankecontacts inthe'Yselectorvrepeaters yaccessible :to the wipers,'-cer=tain offthe contactsaccessible to the special wiper having variousl.electric ipotentials-`'connected thereto, 1 those y'bank contacts accessibleito therspecialwipers-inv eachfswitch. andiinz'allv switohes,fz.having thel .l samepotential" connected thereto,

beingimultipledtoeach other, means.operated-in',responser to V`theinitiation of a-oall by one offsalid -callingsubscribers magnet M286and-groundon `contacts-229. Relay'R315',060k'foriextending'rhis linetoone: of:said 'selectorJ repeaters and` asdescribed: above, ,operatesfully,y connects'the 'switchf ing-relay; R220 totheprivatewiper 393,lockstitself operatedover its upper' winding,^'releasesconnectizonsto"thek main: oce 5.73,- opens its.v original:V operating'.circuit tol restore the releaseunagnetv M286, Aand prepares: acircuiti,65k

toz the fmain office.v by Vway offfsaiclone selector"repeater;meansa'lnsaid. one sselector repeater loperated responsive to a rst anda secondfvseries offimpulses for-repeating saidimpulses-to` the main:oice andl for moving the'wipers sto a'primaryl positionfthereof andthen to a'secondary posi-- t1on.'tl1ereof,1means' .in said one -selectorrepeaterl operated' :responsive I to' itswspecial Wiperencounteringv a-'cer tain"one:'ofsaidfpotentials connectedtothe bank'lcontactaccessible thereto in 'fsaid .l secondary positionfor restor'fourthndigit,V which wefwill assumel tow-be thea1 digit `2',f702yingfthe wipers'to normal, ycontrol means independentfofrelays-:11220, R225; R240,y R260, R315 andiR335wbeing operated.l

Thezline` irelayuR220 fr will' be` restored and reoperated twiceinrresponse to'fsaid fourth digiti 2 tofoperaterrelayR300fand-to:,causeathevertical-nnagnetlM280-ftowraiseL75?)thezimainexchange and lfor-"movingthe=wipersinto'onev saidrbanlc contacts and'foperated'onlyin certainfofthe prim-aryrposltions' ofthe wipers; said thirdementionedl f meansoperated responsive to acertaini third'serieskofA l impulses 'forfrepeating: saidffthird -series aofi irn-p'ul-sesM to of said certainprimary positions thereof, thereby to operate said control means, andmeans in said one selector repeater operated responsive to saidoperation of the control means for moving the wipers to a desiredsecondary position, for extending connections to the wiper set and fordisconnecting the calling line from the main office.

2. The combination claimed in claim l wherein said third-mentioned meansis operated responsive to a certain other third series of impulses forrepeating said other impulses to the main exchange and for moving thewiper into a primary position other than said certain primary positions,and means effective upon a failure of said control means to operate uponreceipt of the third series of impulses for preventing the movement ofthe wipers and for preventing disconnection of the calling line from themain office, whereby connections will be established by way of the mainoiice.

3. The combination claimed in claim 1 together with means operatedresponsive to the special wiper engaging in said inst-mentionedsecondary position a bank contact having a dilerent one of saidpotentials for rendering the wipers ineective, and for preventingdisconnection of the calling line from the main oce, whereby connectionswill be established by way of the main oflice.

4. The combination claimed in claim l together with a second controlmeans independent of said bank contacts and operated in a primaryposition of the wipers other than said certain primary positions, andmeans operated responsive to the operation of said second control meansconsequent to the movement of the wipers into said other primaryposition by the first series of impulses for moving the Wipers to adesired secondary position, for extending connections to the wiper setand for disconnecting the calling line from the main oiiice.

5. The combination claimed in claim 4 wherein the first-mentionedcontrol means includes contacts operated by one set of normal postsprings and wherein said second control means includes contacts operatedby another set of normal post springs.

6. For use in a telephone system having a main ofice and a suboiiicetogether with means including a group of switching selector repeaters insaid suboce for completing connections between lines of callingsubscribers in said suboiiice and lines of called subscribers in saidsuboice and in the main oiiice, each selector repeater having a wiperset, including a special wiper, with a plurality of primary andsecondary positions, bank contacts in the selector repeaters accessibleto the wipers, certain of the contacts accessible to the special wiperhaving various electric potentials connected thereto, those bankcontacts accessible to the special wiper in each switch and in allswitches, having the same potential connected thereto, being multipledto each other; means operated in response to the initiation of a call byone of said calling subscribers for extending his line to one of saidselector repeaters and to the main oiice by way of said one selectorrepeater, means in said one selector repeater operated responsive to arst and a second series of impulses for repeating said impulses to themain ofce and for moving the wipers to a primary position thereof andthen to a secondary po sition thereof, means in said one selectorrepeater operated responsive to its special wiper encountering a certainone of said potentials connected to the bank Contact accessible theretoin said secondary position for restoring the wipers to normal, controlmeans independent of said bank contacts and operated only in certain ofthe primary positions of the wipers, said third-mentioned means operatedresponsive to a certain third series of impulses for repeating saidthird series of impulses to the main exchange and for moving the wipersinto one of said certain primary positions thereof, thereby to operatesaid control means, means controlled by said operation of the controlmeans for again restoring the Wipers to normal, said third meansoperated in response to a fourth series of impulses for moving thewipers to a desired primary position and then to a desired secondaryposition, and means for extending connections to the wipers and fordisconnecting the calling line from the main oiice.

7. The combination claimed in claim 6 wherein said third-mentioned meansis operated responsive to a certain other third series of impulses forrepeating said other impulses to the main exchange and for moving thewiper into a primary position other than said certain primary positions,and means eiective upon a failure of said control means to operate uponreceipt of the third series of impulses for preventing the movement ofthe wipers and for preventing disconnection of the calling line from themain ofce, whereby connections will be established by way of the mainoice.

8. The combination claimed in claim 6 together with means operatedresponsive to the special wiper engaging in said rst-mentioned secondaryposition a bank contact having a different one of said potentials forrendering the wipers ineifective, and for preventing disconnection ofthe calling line from the main oce, whereby connections will beestablished by way of the main office.

9. The combination claimed in claim 6 together with a second controlmeans independent of said bank contaets and operated in a primaryposition of the wipers other than said certain primary positions, andmeans operated responsive to the operation of said second control meansconsequent to the movement of the wipers into said other primaryposition by the rst series of impulses for moving the wipers to adesired secondary position, for extending connections to the wiper setand for disconnecting the calling line from the main oiiice.

l0. The combination claimed in claim 9 wherein the first-mentionedcontrol means includes contacts operated by one set of normal postsprings and wherein said second control means includes contacts operatedby another set of normal post springs.

11. The combination claimed in claim 9 together with other contactsoperated by said other normal post springs consequent to the movement ofthe wipers into said other primary position by the fourth series ofimpulses for forcing the wipers to a position in which a busy signal isreturned to the calling subscriber.

No references cited.

